Scientists have created a robot made entirely from DNA that can be instructed to find diseased cells in the body and deliver a payload to kill or reprogram them, according to a study from Harvard University. The robot was constructed by folding DNA strands into a shape that looks roughly like a clamshell. The researchers programmed the nano-sized device to open in the presence of leukemia and lymphoma cells in a laboratory dish, where they delivered immune system antibodies that caused the cells to self-destruct, according to a report in the journal Science.